problem (Carnegie Foundation, 1990). This finding is complemented by research showing the detrimental effect of absenteeism due to illness on student achievement (Ohlund and Ericsson, 1994).

Infectious agents can be transmitted by person-to-person contact, by droplets or large particles spread by coughing, sneezing, or wheezing, or by fomites (self-innoculation after touching contaminated surfaces). Distinguishing the various transmission modes is difficult, and the role of airborne transmission in respiratory infections is not yet completely understood. It is clear that many factors affect infection transmission, including the number of students in a school, their ages, the degree of crowding in classrooms, teacher-to-student ratios, geographic location, seasonal variation in the activity of common infectious agents, the number of recent immigrants, the proportion of children with chronic health conditions, and the number of young children: Young children have relatively less immunity to common infections and tend to pay less attention to personal hygiene (Hall, 2001; Marchisio et al., 2001; Goldmann, 2001; Brady, 2005; Musher, 2003).

School building factors that influence the transmission of specific infectious agents include the ventilation rate, humidity, filtration effectiveness, the cleanliness of surfaces, and the number, accessibility, and functional state of sinks and toilets (Bloomfield, 2001; Vernon et al., 2003) (Figure 7.1).

Current green school guidelines typically contain few measures related to these building characteristics, although they may address filter efficiencies. Additional measures could be included in future guidelines that might interrupt the transmission of infectious diseases, thereby improving the health of students, teachers, and others.

MODES OF TRANSMISSION FOR RESPIRATORY VIRUSES

The main agents of respiratory infections in schoolchildren, their families, and caretakers are respiratory syncytial virus,1 picornaviruses (especially the three genera enteroviruses, rhinoviruses,2 and parechoviruses3), influenza, adenoviruses,4 parainfluenza viruses,5 measles, and

1

A virus that causes infection of the lungs and breathing passages. Symptoms can include cough, stuffy or runny nose, mild sore throat, fever.

2

The common cold.

3

Causes mainly gastrointestinal and respiratory infections.

4

A group of viruses that infect the membranes (tissue linings) of the respiratory tract, the eyes, the intestines, and the urinary tract.

5

Parainfluenza viruses account for a large percentage of pediatric respiratory infections, including upper respiratory tract infections, laryngotracheobronchitis (croup), bronchiolitis, and pneumonia.



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